(1) Field of the Invention
The present invention relates to a parking lock device for a saddle riding type vehicle called a four-wheel buggy for rough terrain which is maneuvered by a rider straddling the saddle type seat thereof by gripping its handlebars, and in particular relates to a parking lock device for locking the wheels of the vehicle so that it will not be moved when parked.
(2) Description of the Prior Art
A typical saddle riding type vehicle has parking cams arranged in its drum brakes in the left and right rear-wheels so that the rear-wheels can be locked by actuating the drum brakes when it is parked.
Other than the above, there is a parking brake configuration in which the gear shaft of the transmission connected to the engine is locked by arranging a lock gear fixed at one side of the gear shaft of the gear transmission and a parking cam and actuator at one side of a transmission cam drum for making a change in gear so that the distal end of the actuator meshes the lock gear (see Japanese Patent Application Laid-Open Hei 11 No.30991, for example).
The configuration using the gear shaft of the gear transmission and the transmission cam drum needs a long gear shaft and a long transmission cam drum. Hence, the width of the transmission case becomes larger. Since a vehicle of this type generally uses its engine case integrally formed with the transmission case, use of the above configuration affects greatly and needs a serious design change with a large weight increase for the case. Further, since the gear shaft and transmission cam drum should be arranged in a fixed relationship, this greatly restrains the way of attachment of the actuator hence this configuration has difficulties in terms of cost and from a technical viewpoint.
In view of the above problems, it is therefore an object of the present invention to provide a parking lock device for a saddle riding type vehicle, which is compact and can be arranged in the housing for coupling the intermediate shaft to the axle shafts with a light design change.
In order to achieve the above object, the parking lock device for a saddle riding type vehicle of the present invention is configured as follows:
In accordance with the first aspect of the present invention, a parking lock device for a saddle riding type vehicle, wherein the engine power is transmitted as it is being varied in speed to the axle shafts via the final reduction gear which is comprised of an input shaft having a pinion gear at the distal end thereof, a housing axially supporting the input shaft, a bevel gear disposed on the output shaft side and meshing the pinion gear and a carrier axially supporting the bevel gear, includes:
a parking gear fixed on the input shaft;
a pivot element cantilevered and axially supported on a pivot shaft in the housing and having a projection on one side thereof, with respect to the direction of swaying, so that the projection is able to engage the parking gear; and
a cam element axially supported on a cam shaft in the housing and abutting the pivot element on the opposite side with respect to the direction of swaying so as to sway the pivot element, and is characterized in that the pivot element sways as the cam element rotates so that the engagement projection of the pivot element becomes engaged with or disengaged from the parking gear to thereby lock and release parking lock.
In accordance with the second aspect of the present invention, the parking lock device for a saddle riding type vehicle having the above first feature is characterized in on the housing, a cam plate rotatable about the cam shaft and an urging element which rotationally urges the cam plate in one direction about the cam shaft.
In accordance with the third aspect of the present invention, the parking lock device for a saddle riding type vehicle having the above second feature is characterized in that the cam shaft is formed with a claw portion which restrains an excessive rotation of the cam plate due to the urging element in its urging direction and when parking lock is released the claw portion is able to rotate whilst keeping its abutment against the cam plate.
If in general a parking lock device is arranged on the axle shaft on the output side of the final reduction gear, a large braking force is needed. In contrast, in accordance with the present invention, since the parking lock device is arranged in the housing which axially supports the input shaft so as to lock the input shaft on the input side of the final reduction gear, it is possible to reduce the necessary braking force in the proportion of the gear ratio of the final reduction gear, hence provide a compact, lightweight parking lock device at a reduced cost.
Since the pivot element in which a projection engageable with the parking gear is formed on one side with respect to the direction of swaying is cantilevered and axially supported on the pivot shaft in the housing while the cam element abutting the pivot element on the opposite side thereof with respect to the direction of swaying so as to sway the pivot element is axially supported on the cam shaft in the housing, the parking lock mechanism can be made compact by providing the pivot element in the form of a cantilever. Further, since the pivot shaft and the cam shaft are laid out so as to be orthogonal to each other because of their positional relationship with the input shaft, the swaying direction of the pivot element and the rotational direction of the cam element are positioned approximately perpendicularly to each other, thus making it possible to reduce the layout space of the cam element.
It is preferable that the cam element is comprised of a cam shaft supported on the housing and a cam plate rotatable about the cam shaft and an urging element which rotationally urges the cam plate in one direction about the cam shaft. Since the cam plate rotationally urged by the urging element keeps on pressing the pivot element against the lock gear, it is possible to provide a waiting mechanism in a simple configuration.
It is preferable that the cam shaft is formed with a claw portion which restrains an excessive rotation of the cam plate due to the urging element in its urging direction and when parking lock is released the claw portion is able to rotate whilst keeping its abutment against the cam plate. Since the claw portion provided on the cam shaft rotates whilst keeping its abutment against the cam plate when parking lock is released, the waiting mechanism will not work, so that the locking state is undone by force. Therefore, it is possible to perform positive unlocking.
When the actuator shaft is rotated so that the actuator arm separates from the cam plate, the cam plate, urged by the elastic force of the pressing spring, pushes down the engagement piece opposing the release spring so that the engagement piece meshes the lock gear. This meshing fixes the intermediate shaft and the axle shafts hence establishes parking lock for locking the movement of the vehicle. When the actuator shaft is rotated in reverse so that the actuator arm rotates the cam plate to the releasing side, opposing the pressure of the pressing spring, the engagement piece becomes disengaged from the lock gear by the elastic force of the release spring, hence the locking state of the intermediate shaft is released thus creating a drive permissible state in which the axle shafts can rotate.
If the projection of the engagement piece has not yet engaged with the lock gear whilst being held off by its abutment against the raised portion of the lock gear, the engagement piece waits at that position where it abuts the raised portion. Then, as the lock gear turns in a small amount, the projection of the engagement piece meets the indentation of the lock gear so that the engagement piece sways by the elastic force of the pressing spring and becomes in mesh with the lock gear, establishing the locking state.
Finally, since the lock gear, engagement piece, actuator shaft and other associated parts are arranged in the housing, it is possible to provide a compact parking lock configuration by partial modification of the housing with a small increase in weight.